WEDNESDAY, May 2 (HealthDay News) -- Aspirin is just as effective as the blood-thinner warfarin in preventing stroke and death in heart failure patients with a normal heart rhythm, a landmark study indicates.

Although the two treatments are equally effective, researchers from Columbia University in New York City said their findings could prompt more doctors and patients to choose aspirin because it is much cheaper.

The 10-year study was the largest comparison of aspirin and warfarin (Coumadin) in the treatment of heart failure patients. In conducting the comparison, researchers followed more than 2,300 patients in 11 countries on three continents. Study participants were assigned randomly either to aspirin or warfarin, and neither the patient nor their doctor knew which medication each patient was taking.

The investigators found that the combined risk of death, stroke and cerebral hemorrhage during the study period was 7.47 percent for patients taking warfarin and 7.93 percent for patients taking aspirin -- a difference that is statistically insignificant.

Although patients taking warfarin had a nearly 50 percent lower risk for stroke than those taking aspirin, their risk for major bleeding was twice as high. As a result, the researchers argued that the benefits do not outweigh the risks. They noted, however, that taking warfarin for four years or more may be more effective at preventing stroke and death.

"With at least 6 million Americans -- and many more around the world -- suffering from heart failure, the results of the ... study will have a large public health impact," Dr. Walter Koroshetz, deputy director of the U.S. National Institute of Neurological Disorders and Stroke, said in a Columbia University news release. "Patients and their physicians now have critical information to help select the optimum treatment approach. The key decision will be whether to accept the increased risk of stroke with aspirin or the increased risk of primarily gastrointestinal hemorrhage [stomach bleeding] with warfarin."

Although the study, published in the May 3 issue of the New England Journal of Medicine, found aspirin and warfarin to be equally effective, the researchers noted that aspirin may be a more likely choice for doctors and patients.

Like warfarin, aspirin reduces the risk of stroke due to a clot or blockage. Aspirin, however, is cheaper and available over the counter. Warfarin also requires a strict dosing regimen, including regular blood tests to monitor patients' clotting levels.

"Since the overall risks and benefits are similar for aspirin and warfarin, the patient and his or her doctor are free to choose the treatment that best meets their particular medical needs," principal investigator, Dr. Shunichi Homma, associate chief of the cardiology division at New York-Presbyterian/Columbia and a professor of medicine at Columbia's College of Physicians and Surgeons in New York City, said in the news release. "However, given the convenience and low cost of aspirin, many may go this route."